We have been testing out Doom 3 performance, and our first results are with the Radeon 9800XT and an Athlon 64 3200+. We test at several resolutions, and all of the quality settings.

Now high quality does bring a drop in frame rates across the board. Only the 640 resolution is able to stay above 60 frames per second, and you see about a 7 frame per second drop in performance across every resolution except 1280. 1280 drops 3 frames per second to 29.1. This is the resolution I used during my single player play, and for the most part things ran ok. If I became serious I would likely drop back down to 1024X768.